This invention relates to premium quality intermediate moisture vegetables and methods for preparing such vegetables. More specifically, this invention relates to premium quality intermediate moisture vegetables prepared using an infusion cocktail comprising an aqueous solution of (1) a water-soluble, predominantly lower molecular weight, low sweetness carbohydrate, (2) a polyhydric alcohol, (3) salt, (4) a non-inorganic sweetness depressant agent, and (5) nisin-containing whey derived from a nisin-producing culture. This invention also relates to premium quality intermediate moisture vegetables prepared using an infusion cocktail comprising an aqueous solution of (1) a water-soluble, predominantly lower molecular weight, low sweetness carbohydrate, (2) a polyhydric alcohol, (3) salt, and (4) a non-inorganic sweetness depressant agent. After drying to a water activity of about 0.5 to about 0.9, the intermediate moisture vegetables of the present invention are shelf stable. For example, such intermediate moisture vegetables having a water activity of about 0.55 to about 0.65 are expected to be shelf stable for about twelve months under ambient conditions; intermediate moisture vegetables having a water activity of about 0.75 to about 0.85 are expected to be shelf stable for about 90 days under refrigeration conditions. When cooked, these intermediate moisture vegetables provide appearance, texture, and taste similar to that provided by high quality cooked frozen vegetables.
Dried packaged convenience foods or mixes, such as, for example, soups, casseroles, salads, and the like, are popular. Such foods or mixes frequently contain various types of dehydrated vegetables (generally with water activities of less than about 0.5) along with other food components. Unfortunately, such dehydrated vegetables, when cooked, tend to rehydrate slowly, require long cooking times, and generally do not resemble fresh vegetables in terms of color, appearance, texture, and/or nutrition.
Numerous attempts have been made to prepare dehydrated vegetables having improved properties. U.S. Pat. No. 3,623,893 (Nov. 30, 1971) used super-atmospheric pressures (i.e., 200 to 4000 psi) to infuse foods, including vegetables, with an aqueous infusion cocktail containing propylene glycol, potassium sorbate, glycerol, and salt. Of course, the use of such high pressures would involve high capital expense if such a system were used commercially.
U.S. Pat. No. 3,745,027 (Jul. 10, 1073) provided a method for cooking vegetables in an infusion mixture containing, for example, glycerol, salt, propylene glycol, potassium sorbate, and water. For example, diced carrots cooked for 15 minutes in the infusion mixture and then soaked for 6 hours in the infusion mixture were reported to have xe2x80x9cacceptable eating qualities and microorganic stability.xe2x80x9d
U.S. Pat. No. 4,832,969 (May 23, 1989) provides improved dried green vegetables using an infusion cocktail containing a polyhydric alcohol, a sugar, an alkaline buffering system or agent (i.e., sufficient to obtain a cocktail pH of about 6 to 8), an inorganic bittering agent (e.g., KCl and/or MgCl2), a surfactant, salt, and an anti-oxidant (e.g., vitamin E, tocopherol, BHA, BHT, or mixtures thereof). After treatment with the infusion cocktail, the vegetable pieces are dried to a water activity of about 0.3 to 0.85 at a temperature of less than about 135xc2x0 F. The resulting dried green vegetables are reported to have superior color retention for extended time periods even at room temperature storage, superior texture upon rehydration, and excellent rehydration rates.
U.S. Pat. No. 4,946,693 (Aug. 7,1990) provides a process for preparing intermediate moisture vegetables. In this process, vegetables are blanched or cooked, preferably using a microwave oven, and then partially dried (i.e., water content of 45 to 55 percent). The dried vegetables are then dry mixed with salt (and optionally sodium glutamate if the vegetables are not cooked using a microwave oven); an anti-mycotic agent can also be added.
U.S. Pat. No. 5,110,609 (May 5, 1992) provides a method for producing intermediate moisture vegetables wherein the vegetables are partially dehydrated to a moisture content of 26 to 60 percent and then stored in an oxygen free atmosphere.
U.S. Pat. No. 5,925,395 (Jul. 20, 1999) provides a method for preserving vegetables whereby the vegetables are treated with a preservative solution containing water, calcium ions, and optionally ascorbic acid or erythorbic acid. The resulting vegetables are then stored at a non-freezing temperature less than 20xc2x0 C. If stored at ambient temperatures, microbial contamination is possible.
Although these methods can provide improved intermediate moisture vegetables, there remains a need for even further improvements. The present method provides such improvements. Indeed, the present method allows the preparation of intermediate moisture vegetables which are shelf stable and which have significantly improved organoleptic properties. In taste tests, the present intermediate moisture vegetables were often ranked as good as or even better than the original vegetables.
This invention relates to premium quality intermediate moisture vegetables and methods for preparing such vegetables. More specifically, this invention relates to premium quality intermediate moisture vegetables prepared using an infusion cocktail comprising an aqueous solution of (1) a water-soluble, predominantly lower molecular weight, low sweetness carbohydrate, (2) a polyhydric alcohol, (3) salt, (4) a non-inorganic sweetness depressant agent, and (5) nisin-containing whey derived from a nisin-producing culture. Preferably, the infusion cocktail also contains an anti-mycotic agent, a release agent, and calcium lactate.
Although it is preferred that the infusion cocktail contain the nisin-containing whey derived from a nisin-containing culture, infusion cocktails without such nisin-containing whey can also be used in the present invention. Such infusion cocktails comprise an aqueous solution of (1) a water-soluble, predominantly lower molecular weight, low sweetness carbohydrate, (2) a polyhydric alcohol, (3) salt, and (4) a non-inorganic sweetness depressant agent. Preferably, such infusion cocktails also contain an anti-mycotic agent, a release agent, and calcium lactate.
After drying to a water activity of about 0.5 to about 0.9, the intermediate moisture vegetables of the present invention are shelf stable. For example, such intermediate moisture vegetables having a water activity of about 0.55 to about 0.65 are expected to be shelf stable for about twelve months under ambient conditions; intermediate moisture vegetables having a water activity of about 0.75 to about 0.85 are expected to be shelf stable for about 90 days under refrigeration conditions. When cooked, these intermediate moisture vegetables provide appearance, texture, and taste similar to that provided by high quality cooked frozen vegetables.
The present premium quality intermediate moisture vegetables are prepared by a method comprising (a) infusing vegetables with an antimicrobial infusion cocktail at a temperature of greater than about 50xc2x0 F. for about 15 to about 180 minutes, wherein the antimicrobial infusion cocktail comprises an aqueous solution of (1) a water-soluble, predominantly lower molecular weight, low sweetness carbohydrate, (2) a polyhydric alcohol, (3) salt, (4) a non-inorganic sweetness depressant agent, and (5) nisin-containing whey derived from a nisin-producing culture; (b) collecting the vegetables and removing excess antimicrobial infusion cocktail; (c) drying the collected vegetables to a water activity of about 0.5 to about 0.9 to form the intermediate moisture vegetables; and (d) packaging the intermediate moisture vegetables. Preferably, the vegetables subjected to the present process are instantly quick-frozen or freshly prepared. The shelf life of the intermediate moisture vegetables can be adjusted or modified using the final water activity. For example, intermediate moisture vegetables dried to a water activity of about 0.75 to about 0.85 (and properly packaged) are expected to have a shelf life of about 90 days under refrigeration conditions; intermediate moisture vegetables dried to a water activity of about 0.55 to about 0.65 (and properly packaged) are expected to have a shelf life of about 12 months under ambient conditions.
The present invention relates to premium quality intermediate moisture vegetables prepared using an infusion cocktail comprising an aqueous solution of (1) a water-soluble, predominantly lower molecular weight, low sweetness carbohydrate, (2) a polyhydric alcohol, (3) salt, (4) a non-inorganic sweetness depressant agent, and (5) nisin-containing whey derived from a nisin-producing culture. One preferred infusion cocktail comprises an aqueous solution of (1) a water-soluble, predominantly lower molecular weight, low sweetness carbohydrate, (2) a polyhydric alcohol, (3) salt, (4) a non-inorganic sweetness depressant agent, (5) nisin-containing whey derived from a nisin-producing culture, (6) an anti-mycotic agent, (7) a release agent, and (8) calcium lactate. Preferably, the infusion cocktail is an aqueous solution containing (1) about 30 to about 65 percent water-soluble, predominantly lower molecular weight, low sweetness carbohydrates, (2) about 1 to about 15 percent polyhydric alcohols, (3) about 0.1 to about 0.7 percent salt, (4) about 0.1 to about 1 percent non-inorganic sweetness depressant agents, (5) about 1 to 8 percent nisin-containing whey derived from a nisin-producing culture, (6) 0 to about 2000 ppm anti-mycotic agents, (7) about 0 to about 0.5 percent release agents, and (8) 0 to about 3 percent calcium lactate. More preferably, the infusion cocktail is an aqueous solution containing (1) about 40 to about 60 percent water-soluble, predominantly lower molecular weight, low sweetness carbohydrates, (2) about 6 to about 10 percent polyhydric alcohols, (3) about 0.3 to about 0.5 percent salt, (4) about 0.5 to about 0.7 percent non-inorganic sweetness depressant agents, (5) about 2 to about 4 percent nisin-containing whey derived from a nisin-producing culture, (6) 0 to 800 ppm anti-mycotic agents, (7) 0 to about 0.4 percent release agents, and (8) 0 to about 3 percent calcium lactate. Even more preferably, the infusion cocktail is an aqueous solution containing (1) about 40 to about 60 percent water-soluble, predominantly lower molecular weight, low sweetness carbohydrates, (2) about 6 to about 10 percent polyhydric alcohols, (3) about 0.3 to about 0.5 percent salt, (4) about 0.5 to about 0.7 percent non-inorganic sweetness depressant agents, (5) about 2 to about 4 percent nisin-containing whey derived from a nisin-producing culture, (6) about 100 to 800 ppm anti-mycotic agents, (7) about 0.2 to about 0.4 percent release agents, and (8) about 0.5 to about 2 percent calcium lactate. The infusion cocktail generally has a solids content of about 40 to about 75 percent, and preferably about 50 to about 60 percent. The use of such high solids in the infusion cocktail provides a high osmotic pressure and appears to accelerate the infusion rates. One preferred anti-mycotic agent is an approximately 1 to 1 blend or mixture of potassium sorbate and sodium benzoate; one preferred release agent is an high HLB (i.e., about 8 to about 10) soy lecithin. The pH of the infusion cocktail should generally be about 4.5 or higher, preferably about 4.5 to 7, and more preferably about 5 to about 6. Of course, the infusion cocktail can include other components such as, for example, spices, flavorants, other preservatives, nutrients, vitamins, nutraceutical additives, and the like.
The present invention also relates to premium quality intermediate moisture vegetables prepared using an infusion cocktail comprising an aqueous solution of (1) a water-soluble, predominantly lower molecular weight, low sweetness carbohydrate, (2) a polyhydric alcohol, (3) salt, (4) and a non-inorganic sweetness depressant agent. Another preferred infusion cocktail comprises an aqueous solution of (1) a water-soluble, predominantly lower molecular weight, low sweetness carbohydrate, (2) a polyhydric alcohol, (3) salt, (4) a non-inorganic sweetness depressant agent, (5) an anti-mycotic agent, (6) a release agent, and (7) calcium lactate). Preferably, the infusion cocktail is an aqueous solution containing (1) about 30 to about 65 percent water-soluble, predominantly lower molecular weight, low sweetness carbohydrates, (2) about 1 to about 15 percent polyhydric alcohols, (3) about 0.1 to about 0.7 percent salt, (4) about 0.1 to about 1 percent non-inorganic sweetness depressant agents, (5) 0 to about 2000 ppm anti-mycotic agents, (6) about 0 to about 0.5 percent release agents, and (7) 0 to about 3 percent calcium lactate. More preferably, the infusion cocktail is an aqueous solution containing (1) about 40 to about 60 percent water-soluble, predominantly lower molecular weight, low sweetness carbohydrates, (2) about 6 to about 10 percent polyhydric alcohols, (3) about 0.3 to about 0.5 percent salt, (4) about 0.5 to about 0.7 percent non-inorganic sweetness depressant agents, (5) 0 to 800 ppm anti-mycotic agents, (6) 0 to about 0.4 percent release agents, and (7) 0 to about 3 percent calcium lactate. Even more preferably, the infusion cocktail is an aqueous solution containing (1) about 40 to about 60 percent water-soluble, predominantly lower molecular weight, low sweetness carbohydrates, (2) about 6 to about 10 percent polyhydric alcohols, (3) about 0.3 to about 0.5 percent salt, (4) about 0.5 to about 0.7 percent non-inorganic sweetness depressant agents, (5) about 100 to 800 ppm anti-mycotic agents, (6) about 0.2 to about 0.4 percent release agents, and (7) about 0.5 to about 2 percent calcium lactate. The infusion cocktail generally has a solids content of about 40 to about 75 percent, and preferably about 50 to about 60 percent. The use of such high solids in the infusion cocktail provides a high osmotic pressure and appears to accelerate the infusion rates. One preferred anti-mycotic agent is an approximately 1 to 1 blend or mixture of potassium sorbate and sodium benzoate; one preferred release agent is an high HLB (i.e., about 8 to about 10) soy lecithin. The pH of the infusion cocktail should generally be about 4.5 or higher, preferably about 4.5 to 7, and more preferably about 5 to about 6. Of course, the infusion cocktail can include other components such as, for example, spices, flavorants, other preservatives, nutrients, vitamins, nutraceutical additives, and the like.
The infusion cocktail contains a water-soluble, predominantly lower molecular weight, low sweetness carbohydrate. Generally the molecular weight of the low sweetness carbohydrate is less than about 450 g/mole and preferably about less than about 415 g/mole. Especially preferred carbohydrates are high maltose corn syrups. Generally maltose has about 30 percent of the sweetness of sucrose. Maltose is a small molecule which appears to be very effective in infusing the vegetable structure and lowering the water activity. Preferred high maltose corn syrups include Satinsweet 65 and HM 70 (both from Cargill) which have typical viscosities of about 900 and 450 poises, respectively, at about 70xc2x0 F. The HM 70 high maltose corn syrup, which is especially preferred due to its lower viscosity and relatively higher maltose content, contains about 80 percent solids with about 70 percent maltose, about 4 percent dextrose, about 16 percent maltotrioses, and about 10 percent higher molecular weight fractions on a solids basis. The Satinsweet 65 high maltose corn syrup contains about 81 percent solids with about 65 percent maltose, about 4 percent dextrose, about 15 percent maltotrioses, and about 16 percent higher molecular weight fractions on a solids basis. Preferably the only water-soluble, predominantly lower molecular weight, low sweetness carbohydrate present in the infusion cocktail is the high maltose corn syrup. Generally the water-soluble, predominantly lower molecular weight, low sweetness carbohydrates useful in the present invention contain at least about 60 percent, and preferably at least 65 percent, of maltose and dextrose based on the dry solids.
Polyhydric alcohols (i.e., polyols) are also included in the infusion cocktail as humectants and texture enhancers. Generally the polyhydric alcohols useful in this invention are relatively low molecular weight (i.e., less than about 136 g/mole) alcohols having two or more hydroxyl groups. Examples of suitable polyhydric alcohols include such as glycerol (glycerine or 1,2,3-propanetriol), ethylene glycol, erythritol (1,2,3,4-tetrahydroxybutane), pentaerythritol (5-carbon tetrol (tetrahydroxymethyl) methane), sugar alcohols of the general formula CH2OH(CHOH)nCH2OH where n is 2 to 5, propylene glycol, and the like as well as mixtures thereof. Glycerol is the preferred polyhydric alcohol for use in this invention. The polyhydric alcohols appear to keep the vegetable tissue soft and easily rehydratable during cooking; they also serve to lower the water activity.
Salt is also included in the infusion cocktail. Salt tends to balance the taste profile, reduce aftertaste normally associated with glycerol, act as a taste enhancer, and reduce water activity.
The already low sweetness of the infusion cocktail, and the resulting intermediate moisture vegetables, is further reduced using a non-inorganic sweetness depressant agent or agents. Suitable non-inorganic sweetness depressant agent or agents are generally described in U.S. Pat. No. 4,567,053 (Jun. 28, 1986) and U.S. Pat. No. 5,232,735 (Aug. 3, 1993), both of which are hereby incorporated by reference. An especially preferred non-inorganic sweetness depressant agent is 2-(4-methoxyphenoxy)propionic acid (tradename Lactisole(copyright) from Domino Sugar Corp.) or an alkali metal salt thereof with the sodium salt being most preferred. One especially preferred sweetness depressant agent which is commercially available is Super Envision(copyright) also from Domino Sugar. Super Envision(copyright) is reported to contain about 96 percent sucrose, about 3 percent maltodextrin, about 10,000 ppm Lactisole(copyright) (listed as xe2x80x9cartificial flavorsxe2x80x9d), and a maximum of about 1 percent moisture. Inorganic sweetness inhibitors, such as KCl and MgCl2 used in U.S. Pat. No. 4,832,969, should be avoided as they often provide an undesirable, lingering, and conspicuous bitter taste and/or after-taste.
The preferred infusion cocktails of the present invention also employ nisin-containing whey derived from a nisin-producing culture as an anti-microbial agent. For purposes of this invention, the term xe2x80x9cnisin-containing whey derived from a nisin-producing culturexe2x80x9d is intended to include the whey product, separated from the curd, derived from a nisin-producing culture. Generally, such a nisin-containing whey is obtained by any of a variety of equivalent procedures involving the fermentation of a nisin-producing microorganism. In one such procedure, a pasteurized dairy product such as milk or whey is first inoculated with the nisin-producing microorganism. After the dairy product curdles, the nisin-containing whey is separated from the curds of the curdled culture. The curds and whey can be separated by any conventional technique, including, for example, centrifugation, filtration, and the like. This method effectively removes most or essentially all of the microorganisms in the nisin-containing whey. In an alternative procedure, the nisin-containing whey is obtained from the fermentation of a fortified cheese whey composition using nisin-producing microorganisms. In this procedure, after the pH in the fermentation has fallen to about 5.5, the pH is then maintained at this value for 8-10 hrs before allowing the pH to drop further. The nisin-containing whey, separated from the corresponding curds, is then employed in the products and methods of this invention. As used herein, xe2x80x9cnisin-containing whey derived from a nisin-producing culturexe2x80x9d also includes whey described above that has subsequently been reduced in volume to a more concentrated liquid, or that has been completely dried, by evaporation, lyophilization, or comparable procedure. The term relates additionally to such a concentrated or dried whey that is subsequently reconstituted, either partially or completely, by the addition of water or a water-containing composition. Generally, suitable nisin-containing whey for use in the present invention generally contains about 1000 to about 16,000 international units/ml of nisin equivalent activity as determined by well assay using a nisin-sensitive strain of Lactococcus lactis subsp. cremoris. Nisin activity can be determined using the method of Fowler et al. (Techn. Series. Soc. Bacteriol. 8:91-105 (1975)) with sensitive strain of L. lactis subsp. cremoris as an indicator.
Although, the infusion cocktails of the present invention preferably use nisin-containing whey, other nisin-containing non-whey preferments produced by growing a nisin-producing culture on any suitable (i.e., wherein the microorganisms can grow and produce nisin) fermentation medium can be used. For purposes of this invention, xe2x80x9cnisin-containing wheyxe2x80x9d is also intended to include such nisin-producing cultures prepared using other fermentation medium. Such alternative fermentation media should include metabolizable soluble carbohydrates (such as, but not limited to, glucose, fructose, sucrose, lactose, maltose, galactose, and the like), soluble proteins (milk, cereal hydrolysates, meat and egg byproducts, fish and seafood, and legumes), and other growth factors necessary to support the growth of culture (e.g., yeast extracts).
The preservative and stabilizing effects of such nisin-containing whey have also be used in the preparation of other food products by the assignee of the present application. Such food products are described in applications entitled xe2x80x9cStabilization of Cooked Meat Compositions Using Whey from Nisin-Producing Culturesxe2x80x9d, U.S. Ser. No. 60/098,465, filed Aug. 31, 1998; xe2x80x9cStabilization of Mayonnaise Spreads Using Whey from Nisin-Producing Culturesxe2x80x9d, U.S. Ser. No. 60/098,516, filed Aug. 31, 1998; xe2x80x9cStabilization of Fermented Dairy Compositions Using Whey From Nisin-producing Culturesxe2x80x9d,
U.S. Ser. No. 60/098,518, filed Aug. 31, 1998; and xe2x80x9cStabilization of Cream Cheese Compositions Using Nisin-Producing Culturesxe2x80x9d, U.S. Ser. No. 60/098,472, filed Aug. 31,1998, and are incorporated hereby in their entireties by reference.
The infusion cocktails may also contain other optional ingredients or components such as, for example, spices, flavorants, other preservatives, nutrients, vitamins, nutraceutical additives, and the like so long as they do not adversely effect the organoleptic and/or stability properties in a significant manner. Suitable vitamins that may be included in the infusion cocktail include, for example, vitamin A, vitamin C, vitamin D, vitamin E, B vitamins, niacin, folate, folic acid, and the like as well as mixtures thereof. Suitable minerals include, for example, salts of metal nutrients, wherein the metals are chosen from among calcium, magnesium, copper, iron, zinc, chromium, and the like as wells as mixtures thereof; salts of inorganic minerals such as, for example, phosphate, sulfate, chloride, and the like as well as mixtures thereof can also be used. Suitable antioxidants include, for example propyl gallate, octyl gallate, dodecyl gallate, butylated hydroxyanisole, butylated hydroxytoluene, and the like as well as mixtures thereof. Suitable probiotics include, for example Acidophilus Bifidobacterium, Lactobacillus Johnsonii, and the like as well as mixtures thereof. Suitable botanicals include, for example St. John""s wort, ginseng, ginkgo biloba, and the like as well as mixtures thereof. Of course, as those skilled in the art will realize, other vitamins, minerals, antioxidants, probiotics, and botanticals can also be used in the present invention. The amount of such optional ingredients can, of course, vary considerably depending on the specific nutrient or mineral added (and its recommended daily requirement) and the targeted consumer. For example, macronuterients (e.g., calcium) can be added at relatively high levels (i.e., up to about 5 percent) whereas other trace minerals, vitamins, and other additives (i.e., generally materials having daily adult requirements in the milligram range or lower) will normally be added at much lower levels.
Especially preferred optional ingredients include anti-mycotic agents, release agents or emulsifiers, and calcium lactate. Anti-mycotic agents can be included in the present infusion cocktail at 0 to 800 ppm, preferably at about 100 to 800 ppm. Especially preferred anti-mycotic agents include sodium benzoate and potassium sorbate. An especially preferred anti-mycotic agent is blend of sodium benzoate and potassium sorbate which, when added to the infusion cocktail, provides about 100 to about 400 ppm of each compound. Release agents can be incorporated into the present infusion cocktail at a level of 0 to about 0.4 percent, preferably at about 0.2 to about 0.4 percent. Release agents include lecithin, high stability vegetable oils, mono and diglycerides, polyoxyethylene sorbitan monooleate (ie.g.,Tween 80(trademark)), mineral salts of fatty acids, emulsifier-oil blends, and/or emulsions thereof. A preferred release agent is a high HLB (i.e., about 8 to about 10) soy lecithin. An especially preferred release agent is Precept 8160 (Central Soya Co.) which is a powdered, deoiled, refined, and enzyme-modified soybean lecithin having an HLB of about 9. The use of such a release agent improves the handling characteristics of the infused vegetables during the remainder of the process. Calcium lactate can be included in the infusion cocktail at a level of 0 to about 3 percent, and more preferably present at about 0.5 to about 2 percent. A suitable calcium lactate can be obtained from PURAC America as the pentahydrate. Calcium lactate provides a number of benefits since it can potentially act as a secondary antimicrobial agent, as a water activity depressant, as a pH modifier, and as a highly water-soluble and bio-available source of calcium.
The infusion cocktail is prepared by simply mixing or combining the components with gentle agitation to form an essentially homogenous slurry, suspension, or infusion bath. The pH of the infusion cocktail should generally be about 4.5 or higher, preferably about 4.5 to 7, and more preferably about 5 to about 6. Normally, the infusion cocktail or bath is heated to, and held at, a temperature of greater than about 165xc2x0 F. for about two minutes and then cooled to its operating temperature. Preferably, the infusion cocktail is maintained at an operating temperature of about 50 to about 120xc2x0 F., preferably about 70 to about 120xc2x0 F., during use. Using these infusion cocktail formulations, intermediate moisture vegetables which are shelf stable and, when cooked, provide appearance, texture, and taste similar to that provided by high quality cooked frozen vegetables can be prepared. Moreover, the intermediate moisture vegetables of this invention readily, quickly, and uniformly rehydrate when cooked. Such intermediate moisture vegetables are ideally suited for use in dry mixes such as soups, casseroles, salads, oriental or stir fry type dishes, and the like. Of course, the infusion cocktail can include other components such as, for example, spices, flavorants, other preservatives, nutrients, vitamins, nutraceutical additives, and the like.
The intermediate moisture vegetables of the present invention are prepared by (a) infusing vegetables with the antimicrobial infusion cocktail of the present invention at a temperature of greater than about 50xc2x0 F. for about 15 to about 180 minutes; (b) collecting the vegetables and removing excess antimicrobial infusion cocktail; (c) drying the collected vegetables to a water activity of about 0.5 to about 0.9 to form the intermediate moisture vegetables; and (d) packaging the intermediate moisture vegetables. The process of the present invention may be operated in batch, semi-continuous, or continues mode as desired. Generally, the present process is carried out at ambient pressures. The present invention can be used to prepare a wide variety of green, yellow, orange, and red vegetables. Such vegetables include, for example, carrots, various types of peppers, broccoli, various types of peas and pea-pods, cauliflower, onions, tomatoes, mushrooms, zucchini, corn, celery, asparagus, green beans, water chestnuts, bamboo shoots, and the like. Generally, the vegetables are first cut into appropriate sizes (generally pieces of xc2xdinch or less in their longest dimension) prior to infusion; larger pieces can be used, if desired, so long as the infusion process is modified (e.g., increased temperatures and/or duration) to allow for sufficient infusion of the cocktail. Of course, smaller vegetables such as peas and pea-pods can be, and preferably are, used whole without any reduction in size. Both frozen (especially the instantly frozen type) vegetables and fresh vegetables can be used in the present invention. The vegetables are preferably blanched (e.g., cooked in a water bath at about 165xc2x0 F. or greater for up to about 10 minutes) prior to the infusion process.
The vegetables, reduced in size if appropriate, are placed in the infusion cocktail. The vegetable pieces should remain in the infusion cocktail at a temperature and for a time sufficient to allow the infusion cocktail to infuse into, and preferably throughout, the internal vegetable structures. Generally, infusion is considered sufficient if the vegetables obtain a solids level of at least about 30 percent. Generally, a temperature of greater than about 50xc2x0 F. and a time of about 15 to about 180 minutes is sufficient. Preferably, the infusion cocktail is at, or heated up to, about 70 to about 120xc2x0 F., and more preferably, about 80 to about 100xc2x0 C.; preferably, the vegetable pieces remain in the infusion cocktail for about 45 to about 75 minutes. Preferably the vegetables are subjected to gentle agitation during infusion to provide more uniform uptake of the infusion cocktail. The present invention can be operated in a batch, semi-continuous, or continuous manner. If desired, the infusion cocktail can be reused by adding make-up ingredients and/or fresh infusion cocktail.
Once infusion is complete, the vegetables pieces are removed from the infusion cocktail and excess liquid (i.e., infusion cocktail) is removed from the outer surfaces of the vegetable pieces. Generally, the excess liquid is removed by draining (with or without gentle agitation) or more active processing techniques such as, for example, compressed gas or air sprays or blades (e.g., passing the vegetable pieces through a sterile air curtain), centrifugation, and the like. Generally, water washes are not necessary or desirable. After the excess liquid is removed, the vegetable pieces are then dried to a water activity of about 0.5 to about 0.9 using conventional drying techniques to form the intermediate moisture vegetables. The water activity can be adjusted depending on the use intended for the intermediate moisture vegetables. For example, intermediate moisture vegetables dried to a water activity of about 0.75 to about 0.85 (and properly packaged) are expected to have a shelf life of about 90 days under refrigeration conditions; intermediate moisture vegetables dried to a water activity of about 0.55 to about 0.65 (and properly packaged) are expected to have a shelf life of about 12 months under ambient conditions. It is generally preferred that gentle drying conditions for relatively short time periods be used to prevent case hardening, ensure fast equilibrium after drying, and quick rehydration when cooked or otherwise prepared for consumption.
If desired, the infused vegetable pieces may be treated prior to drying with, for example, release agents such as lecithin, high stability vegetable oils, and emulsions thereof in order to improve handling of the final product. Such a treatment, generally at a level of about 0.1 to 0.5 percent, can reduce surface adhesion and/or dumpiness of the vegetable pieces during and after the drying process (including the final product). Other additives can also be applied with the lecithin and/or high stability vegetable oils. Such additives could include spices, flavorants, nisin-containing cultured whey or other nisin-containing compositions, other preservatives, nutrients, vitamins, nutraceutical additives, and the like. Alternatively, the lecithin, high stability vegetable oils, and emulsions thereof could also be incorporated in the infusion cocktail.
Once dried and cooled, the intermediate moisture vegetables can be packaged. They may be packaged separately or combined with other ingredients before packaging (e.g., meal kits). Preferably, the packaging material is designed to prevent, or at least significantly reduce, color and quality degradation, deterioration, or loss during storage. Preferably, the intermediate moisture vegetable are sealed in oxygen impermeable and light resistant or light proof packaging materials such as, for example, aluminum-polyester film under substantially oxygen-free conditions. Such substantially oxygen-free conditions can be obtained, for example, by inert gas (e.g., N2 or CO2) flushing prior to sealing or using vacuum packing techniques. The resulting intermediate moisture vegetables provide shelf stable, high quality vegetables having, when cooked or rehydrated by the consumer, organoleptic properties similar to instantly frozen or fresh vegetables.
The following examples are intended to illustrate the invention and not to limit it. Unless otherwise indicated, all percentages using in the present specification are by weight.